Fuel injection pumps for internal combustion engines



Oct. 17, 1961 H. H. B. MINETT FUEL INJECTION PUMPS FOR INTERNAL COMBUSTION ENGINES Filed Aug. 5, 1958 U12/Z241, 77.0 PNB.

United States Patent O 3,004,496 FUEL INJECTION PUMPS FOR INTERNAL COMBUSTION ENGINES Herbert Hargrave Basil Minett, Chalfont, St. Peter, England, assignor to D. Napier & Son Limited, London, England, a company of Great Britain Filed Aug. 5, 1958, Ser. No. 753,333 Claims priority, application Great Britain Feb. 28, 1956 2 Claims. (Cl. 103-154) This invention relates to fuel injection pumps for internal combustion engines, of the kind comprising a barrel containing a plunger, fuel being forced by the plunger out of the barrel through a spring-loaded delivery valve contained in a valve chamber and into a fuel delivery pipe or pipes leading from the delivery valve chamber to one or more injectors which spray fuel into the engine cylinder when the plunger is advanced along the barrel by a cam, the return stroke of the plunger being effected by a spring` It is an object of the invention to provide a fuel injection pump in which the delivery valve, with its spring and chamber, the barrel, the plunger, the plunger return spring, and a cam follower are arranged as an assembly removable as a whole from the pump body.

It has previously been arranged to make certain parts of the pump in the form of an assembly removable as a whole from the pump body but such assembly has not hitherto included the cam follower. The distance of the head of the plunger from the point on the cam surface which engages the cam follower must be yaccurately set and maintained, and for this purpose it is customary to provide a packing shim of appropriate thickness between the cam follower and a tappet at the base of the plunger. When dismantling a pump in which the cam follower does not form part of the removable assembly, there is a risk of this packing shim getting lost or interchanged with a similar packing shim of different thickness, especially when the pump body houses several similar pumps. The present invention avoids this risk because the cam follower forms an element of the said removable assembly so that such packing shim will be withdrawn with the assembly and form part of it.

It is a further object of the invention to provide a fuel injection pump in which the plunger is rotatable in the barrel by means of a control pinion (which may either be a complete pinion or a sector of a complete pinion), the control pinion also forming part of the said removable assembly.

lt is a further object of the invention to provide a fuel injection pump in which the removable assembly can be pre-adjusted away from the pump body and inserted into different bores of the same pump or even into a bore of a different pump without further readjustment being required.

rlhis application is a continuation-impart of my copending application Serial Number 635,657 for Fuel Injection Pumps for Internal Combustion Engines, filed Ianuary 23, 1957, now abandoned.

The invention may be performed in various ways and one particular form of fuel injection pump embodying the invention will now be described by way of example with reference to the accompanying drawings, in which:

FIGURE 1 is a view of the pump in vertical section;

FIGURE 2 is a fragmentary cross-section taken on the line A-A in FIGURE l; and

FIGURE 3 is a top elevational view of the locating plate and a fragmentary portion of the delivery valve chamber.

The pump shown in the drawings comprises a cast body made of aluminum or aluminum alloy accommodating a pump barrel 11. In the barrel there recipro- 3,004,496 Patented Oct. 17, 1961 cates a pump plunger 12. YThe upper part of the barrel 11, which is made in one piece with the lower part, constitutes a delivery valve chamber 13. This chamber contains a delivery valve =14 which works in a removable guide and sleeve member 15 and which is urged towards its seating by a compression spring 16. Screwed on to the upper end of the delivery valve chamber 13 is a T-connector 17 to which can be attached fuel delivery pipes (not shown) leading to the injectors.

At the lower end of the pump plunger 12 there is. a tappet 18 in the form of a flange. The upper surface of this flange forms a seating for the lower end of a plunger return spring 19, and the under surface of the fiange seats on a packing shim 20 which in turn rests on a cam follower body 21. The cam follower |body has an upwardly extending sleeve portion 68, and there is a circlip 69 in a groove formed in the inner surface of portion 68 which prevents unintentional withdrawal of the tappet 18 and the shim 20 from the cam follower body 21. The cam follower body 21 includes a roller 22 which is adapted to engage a cam (not shown) in the cam body of the pump and which'is rotatablymounted in the body 21 on a transverse pin 23.

Rotatably mounted around the bottom of the barrel 11 there is a control pinion 24 having a central bore and a downwardly-extending sleeve 25 provided with a vertical slot 26 and a cut-away portion 40. At the bottom of the plunger 12 there is ya reduced cylindrical portion 41, a neck 42 and a flange'43. A flange 44 partly surrounds the cylindrical portion 41 and has a at portion 50 tangential with said cylindrical portion 41. Mounted on the cylindrical portion 41 is a sleeve 45 having a lateral nose 46 which enters slot 26. The sleeve 45 is pressed against the flange 44 by a spring 47 which abuts against a collar 48 retained by a circlip 49 which occupies a groove near the bottom of the cylindrical portion 41. A flat portion of said sleeve 45 at the back of the nose 46 engages said flat portion 50 of the flange 44 so that the sleeve 45 cannot rotate relatively to the plunger 12. The flanged end 43 fits in an open-ended undercut groove in the tappet 18. While the plunger 12 can be reciprocated in the barrel relatively to the pinion 24 with the nose 46 sliding up and down in the slot 26, the rotational position of the plunger in the barrel is determined by the angular position of the pinion 24 about the longitudinal axis of the barrel. The pinion 24 is engaged by a worm 28 extending lengthwise through the pump body, the rotational position of which determines the angular position of the pinion 24. Extending around the segment of the pinion 24 that is not engaged by the worm 28 there is a sleeve 29 the upper end of which bears against a shoulder 30 on the barrel 11 and a lower internal flange 31 of which acts as an abutment for the plunger return spring 19.

Immediately below the pinion 24 the sleeve 29 has an upper internal flange 51, there being an annular chamber 52 defined between the flanges 31 and 51. Projecting down into the bore of the pinion 24 is a cylindrical extension 53 ofthe barrel 11, which extension has a groove 54 near its lower end. The sleeve 25 of the pinion 24 has apertures 55 around its periphery normally aligned with the groove 54, and a circlip 56 fits around the sleeve 25 in the chamber 52 with V-shaped indentations passing through the apertures 5-5 into the groove 54 to locate the pinion 24 axially on the extension 53. Apertures 57 in the sleeve 29 give access to the chamber 52, when the pump assembly is withdrawn from the pump body, to permit the fitting and removal of the circlip 56 and facilitate dismantling of the pump assembly.

The parts so far described with the exception of the body 10 and the worm 28 constitute an assembly removable as a whole from the pump body 10, the pump body having a stepped bore 32 to accommodate the assembly. 4The distance `between the head 60 of the plunger 12 and the lowest point 61 of the cam follower roller 22 must be accurately set, :since this distance affects the injection timing. This accurate setting is adjusted by selecting a lpacking shim 20 of appropriate thickness. Since the thicknesses of the packing shims of different pumps may vary, it isimportant Vthat they must not thereafter be indiscriminately interchanged, for instance in the course of ordinary workshop maintenance. iSince the packing shimforms a part of the said assembly which, as indicated, is removable as a Whole from the pump body vwhen requiring skilled servicing or repair, tthere is no risk of the packing shim being separated 'from the rest of the assembly other than bythe responsible servicing or repairing mechanic.

To secure the assembly in place in the body there is Va ilange 33 around the delivery valve chamber 13, which ange rests upon a machined .surface 34 of the pump body 10 to determine ,the extent to whichthe assembly can be inserted into the body. `The assembly is held .down with .the auge .'33 engaging the surface 34 by studs 35 .which pass through clearance holes or arcuate .slots Tin the .flange 33 and screw into the pump body '170.

The outer surface o f the delivery valve chamber 13 has a portion just above the flange 33 provided with vertical splines or serrations 63. A locating plate ,36 has a splined `portion `64 which engagesin the splines 63 and lits .over one of the 4studs 35 to ,locate .the remova- ,ble assemblyin a particular Aangular position .in the pump body. The injection timing is iniluenced .by the angular ,position of the removable assembly inthe body 10, so the Correct determination and retention of angular posiv.tion is important. ,Tests can be made in a test pump rig to ascertain the correct angular position for any given assembly. Asuitablelocatng plate 36 corresponding to this 4position is then selected and marked to identify it with-this assembly. Then Vif this locating .plate is retained with this assembly, the assembly can 'be inserted in any bore of any pump unit 10, and turned into a position in which the 'locating plate will tit. This position is the correct angular position, and no further skilled adjustment is required. Removable assemblies according to the invention can therefore be pre-adjusted by lskilled labour and by the .use of suitable equipment, and tted in pump bodies so required without requiring :furthm skilled adjustment.

What I claim as my invention and desire to secure by Letters `Patent is:

1. A fuel injection pump for an internal combustion engine comprising a pump body, a housing providing an integral barrel portion and a delivery valve portion, a plunger which can be reciprocated in said barrel portion, a delivery lvalve, a seating for said deliver-y valve, a delivery .valve spring biasing said delivery valve towards said seating, said delivery valve portion enclosing said delivery valve and said seating and saidl delivery valve spring, a return spring -which urges `said plunger in a direction away from said delivery valve, a tappet connected to said plunger, a cam 4follower roller, cam follower roller support means, a packing shim spacing said tappet from said .cam iollower roller .support means, retaining means retaining `said stappet Vin connection with said cam follower roller support means, said housing, said plunger, said delivery valve, said delivery valve seating, said delivery valve spring, said return spring, said tappet, said cam follower roller, said cam follower roller support means, said vpacking shim and said retaining means constituting al1-assembly removable as a whole from said pump ybody, a 4-locating member which engages said housing to prevent relative angular movement, and means securing lsaid locating member :in a xed position on said body.

'2. A fuel injection pump according to claim l in which said removable assembly also includes a control pinion rotatable -on said lbarrel `portion and means connecting said control pinion to said plunger which permits rela- :tive movement of Isaid plunger and said control pinion only -in the vaxial direction.

References Cited in the tile of this patent UNITED STATES PATENTS 1,886,930 Alder Nov. 8, 1932 ,1,916,151 'ilhaheld Oct. 9, 1934 2,007,871 Oldham July 9, 1935 2,097,415 Hurst et al Oct. 26, 193.7 2,185,144 `ld-wards Dec. 26, 1939 2,185,146 Edwards Dec. 26, 1939 2,573,344 Larsh Oct. 30, 1951 2,717,805 Seifert etal Sept. 13, 1955 FOREIGN PATENTS 464,883 Italy July 26, 1961 622,708 Great .Britain May 5, 1949 890,619 France Nov. 8, 1943 

